In composting, microorganisms decompose organic matter into compost. This compost can be useful as fertilizer. Materials necessary for composting include a carbon source, a nutrient source (in particular a nitrogen source), water and oxygen. When materials are combined, aerobic microorganisms metabolize the organic material to produce compost. This metabolism also generates heat. Sometimes this can be seen as steam rising from a compost pile.
Oxygen must be available to an aerobic composting system for use by aerobic microorganisms. In dynamic composting systems, the compostable materials are periodically turned to expose them to fresh air. In static composting systems, the compostable materials are not turned and must be aerated by various means.
Static composting methods include in-vessel composting and open-pile composting. In open-pile composting, the compostable material is piled on the ground or on a platform, and possibly covered with coversheet. In in-vessel composting, organic material is contained within a walled container. In both cases, oxygen must be provided to the compost pile. For air to move through the pile, the pile cannot exceed a certain density, e.g., no more than about 800 pounds per cubic yard, and must contain sufficient air passages to permit flow to bring air in contact with the aerobic bacteria. A solid homogeneous material is disadvantageous for aerobic composting.
In forced aeration systems, air is forced into the compost pile. Forced aeration systems include positive aeration and negative aeration. In positive aeration systems, air is pumped into the compost pile. This can be done, for example, by providing perforated pipes through the base of the pile. Air is pumped into the pipes. In negative aeration systems, air is suctioned into the pile. Both systems require energy to force the air through the pile.
Vegetable material (e.g., greenwaste) is a common carbon source used in composting. Certain animal-based materials also provide nutrients, such as nitrogen. Animal products can be rich in nitrogen and also have been used as a source of nitrogen. This includes, for example, animal excrement (manure). Human excrement (urine and/or feces) (also called “night soil” or “humanure”) also has been used in composting. However, animal excrement, including human excrement, can include microorganisms pathogenic to humans. To use compost made from such materials as fertilizer, such pathogens must be reduced or eliminated.
U.S. Pat. No. 4,552,484 refers to a system for field disposal of human feces through the use of composting containers that prevent the spread of intestinal bacteria, including virulent pathogens, which otherwise would occur when wilderness visitors practice shallow burial of feces. This is said to be accomplished by providing biodegradable containers and following a pre-set method of disposal.
U.S. Pat. No. 5,228,984 refers to a system and method for composting feces and treating. Human feces is said to be collected within a composting retainer and exposed to sufficient air and water to allow the feces to compost, thereby forming compost product. Urine is said to be collected within an urine treatment retainer which is at least partially partitioned from the composting retainer and wherein the urine is passed through a substrate supporting aerobic nitrifying bacteria, thereby nitrifying a significant portion of the ammonium ions in the urine to form liquid product. The compost product is said to be suitable for subsequent use, such as fertilizer or for use in forming a mixture with soil to form topsoil.
U.S. Pat. No. 5,879,931 refers to an aerobic fermentation promoting device, a fermentation system and organic compost prepared by the system. The device is said to promote aerobic fermentation of compost materials by periodically mixing the compost materials together and by letting the compost materials come into contact with the outside air. The device is said to be installed in a fermentation tank and has a rotatable screw conveyor unit, at least one bucket elevator, a drive unit and a steering unit. The compost is said to be produced by charging moisture control materials in the tank, uniformly spraying excrement on the surface of the moisture control materials, mixing the compost materials together using the fermentation promoting device after lapse of four to seven days since spraying of the excrement, and adding new moisture control materials and new excrement to existing compost materials.
U.S. Patent Application 2007-0111305 refers to systems and methods for the generation of compost. In one embodiment, the system for generating compost is said to comprise an aeration floor having a plurality of gas flow apertures that connect to a network of gas flow channels, and a compost cover constructed of a gas and liquid impermeable fabric that is provided with a plurality of ports that permit the passage of gas and liquid through the compost cover. A compost biomass is said to be placed on the aeration floor and the compost cover is placed over the compost biomass. An air suction manifold, connected to an outlet of the gas flow channels, is said to draw exhaust gases from the compost biomass, through the plurality of gas flow apertures and through the gas flow channels. The exhaust gases are then said to be conveyed to an air distributor and directed to an odor control device for substantially eliminating odors.
U.S. Patent Application 2012-0165215 refers to methods and systems for designing and using organism-specific and/or operational taxon unit (OTU)-specific probes.
U.S. Pat. No. 782,493 refers to systems and methods for generating compost.
The statements in the Background are not necessarily meant to endorse the characterization in the cited references nor are the cited references admitted prior art.